The present invention relates to testing machinery, and more particularly to a self-aligning multi-functional test machine which is capable of multi-axle alignment to carry out both torsion and tension-compression tests for a specimen.
Prior art test machine for carrying out tension-compression and swivel test of a specimen includes generally an upper crosshead and a lower crosshead wherein each of the crossheads has an extension and a specimen grip at the end of the extension. The two grips have to align with each other on a center line between the upper and lower crossheads so that the specimen is limited to a linear arrangement to accept a load test U.S. Pat. No. 4,869,112 entitled screw-driven actuator for test from MTS system corporation, which is a device can perform both tension-compression and swivel driven tests. However, the interior of its lower crosshead is composed of a vertical acting oil cylinder and a swivel acting oil cylinder which are rather sophisticated. Besides, there is no any self-aligning system between the upper and lower grips to balance the inclination and shear resulted of the test. Because a linear displacement transducer (LVDT) and a rotation displacement transducer (RVDT) have to be combined therewith, so there is no space inside the lower crosshead to dispose the above self-aligning system. Thus a previously developed self-aligning device by MTS system corporation (U.S. Pat. No. 4,843,888) is adopted to compensate this defect. The self-aligning device includes principally a single pullrod inclination structure which enables to function single axle alignment for a specimen. Nevertheless, it belongs to an externally added equipment that dooms to increase the errors and decrease the distance between the upper and lower crossheads so as to reduce the admittable length of test.
The present invention is arisen to obviate and/or militate the aforediscussed disavantages and provides an upper crosshead including multi-axle alignment system and a lower corsshead including a multiple oil cylinder which is capable of both linear and swivel operations.